Drill



y 1936- w. J. MOCALLUM 2,042,114

DRILL Filed April 23, 19:54

U7. I M C aTluTfi Patented May 26, 1936 UNITED STATES 9 Claims.

This invention relates to drills and more particularly to those employed in boring rock and the like wherein it is economical to use removable bits. The object of this invention is to provide apparatus of this character in which the means for locking the bits are so formed that the bits will remain in position on the end of a drill-head under all working conditions and without danger of accidental removal therefrom.

I attain my object by forming the locking means integral with the bits and drillhead. Each bit is provided with a tang having its free end reduced in thickness or bifurcated so that it will respectively enter one or two parallel sided slots formed in the end of the drill-head. These slots are directed outwardly relative to a plane passing through the axis of the drill-head and in the case of the tangs having bifurcated ends, the slots diverge from the said plane whereby the reduced part of the tang is displaced laterally when it is driven into a slot and the bifurcated parts are spread apart as they are driven into the slots. The bits are thus locked from longitudinal displacement and as the lockingmeans is positioned within the drill-head and takes no percussive thrust, all danger of its being damaged by contact with the rock or other material being drilled is eliminated.

The constructions are hereinafter more fully described and are illustrated in the accompanying drawing in which Fig. 1 is a longitudinal section of part of a drillhead;

Fig. 2 an end view thereof;

Fig. 3 a perspective view of a bit;

Fig. 4 an end view of a retainer;

Fig. 5 a cross section of a retainer showing the bits in position therein;

Fig. 6 a side elevation of part of a drill-head showing the bits and retainer in position thereon;

Fig. '7 an end view of the parts shown in Fig. 6;

Fig. 8 an end view of a modified form of bit; and

Fig. 9 a detail showing the bit in Fig. 8 in position in a drill-head.

In the drawing like numerals of reference indicate corresponding parts in the different figures.

I is a drill-head which may be formed on or secured in any suitable manner to the drill-rod 2. The end l of the drill-head remote from the drill-rod is provided with a plurality of radially directed wings I having flutings I therebetween. In the end faces of these wings may be formed grooves l which extend transversely of the axis of the drill-head. In the bottom of each groove are formed one or two slots I, each having its sides I substantially parallel to one another. When two slots are formed at the bottom of each groove they converge in the direction of the axis of the drill-head towards the end l The drill- 5 head is provided with the usual central passage l and this passage is counterbored at l adjacent the grooves and slots.

The bits or nibs 3 are provided with cutting edges 3 and with tangs 3 adapted to be re- 10 ceived in the grooves I When each of the grooves is provided with two slots I each tang is bifurcated and the bifurcated parts 3 of a tang are adapted to be received in the outer ends of the slots I As the parts 3 are driven into the 15 slots they are displaced laterally by the inner sides of the slots and are thus spread apart to engage the outer sides of the slots whereby the bits are locked from longitudinal displacement. Preferably the bifurcated parts 3 of each tang 20 3 do not extend the full length thereof so that a neck is formed at 3 whereby that portion of each tang in engagement with the sides I of its groove I is of maximum width and strength.

The above mentioned inner sides of each slot l form a wedge having its apex adjacent the front end l of the drill-head. Preferably the wedges are formed by milling the drill-head to form the slots but, if desired, the wedges could be separate parts secured in position between the outer sides of the slots.

To facilitate the assembly of the bits 3 and drill-head I, Imount the bits in a retainer 4 which is shaped to correspond to the end I and is provided with a plurality of tang receiving openings 4 which are spaced to correspond to the grooves I and thus the slots l The underside of the retainer is provided with a flange 4 adapted to be received in the counterbore l to align the central opening 4 in the retainer with the central passage I in the drill-head. By placing the tangs 3 carried by the retainer in the grooves i and using a hammer having a head large enough to engage all the bits, the tangs may be simultaneously forced into locking engagement with the slots I The excess metal 4 around the ends of the openings 4 which metal is necessary to close the latter and hold the tangs from lateral displacement while the bits are carried in the retainer, is subsequently hammered over the sides of the wings I. This metal is soon worn away when the drill is put in use but there is no tendency for the bits to be displaced laterally from the drillhead. 5

The retainer 4 is preferably made of steel which is milder than that used in the drill-head I so that it forms a shield for the end of the drillhead and a cushion between the latter and the undersides 3 of the bits 3. Clearance is provided between the ends of the bifurcated parts 3 and the bottoms of the slots l so that, should the retainer be compressed and the tangs moved farther into the slots, the tangs will be further spread to lock themin their .new position. .Of course a new retainer is used every'utime .the"bits are replaced.

The cutting edges of the bits are hardenedaand the tangs thereof are annealed to condition them for their particular use.

Referring to Figs. 8 and 9, armodified. formof my device is shown therein'in 'wliichthe bit'3'is provided with a tang 3 havingitsfreeieirdfiireduced in thickness and preferably directed .outwardly at 3 With this construction onlyo'ne slot l is required :atctherb'ottomofieachigroove H thus increasing the amount of vmetal :between the slots l in adjacent wings l aand'reducing the chances of breakage of-the heads between the slots especially in small drills. .Whennthesingle slot l is used it is necessary :to makezitandthe reduced=end of the bit in accordance with :the direction of rotation of thefdrilhso .that themesultant 70f theforces actingagainst=-the cutting edge 3 will befso directed thateanytendency to rock the bit will be resisted -.by the outward1y directed end of thetang.

It will be distinctly understood .that the ediverged slots l may be formed at theend I of the drill-head instead of forming them-at the bottoms of-:the.-grooves without departing-from the spirit of my invention.

What I claim as mylinventionis:

l. A drill-head havingtwo-substantiallyparallel sided slots extending vtransversely:of and -;diverging in the direction 13f theaxisoflthecdrillhead; and a bit having "a .bifurcated :tang, the parts of which are adapted to- .be received in'ithe slots andto be displaced laterallyitherebytoilock the bit from longitudinaldisplacement.

2. A drill-head constructed assetfortlrinclahn l in which a transverse grooveiis formed in :the end of the drill-head,stheislots.communicateiwith the bottom of theggroove, and-the tangziszformed .with a solid neck adapted=to engagewthessides-tof the groove.

v3. A drill-head having a plurality-:ofssubstantially' parallel sided slotsrextendig ztransversely of and directed at an acute'angleto atplane passthrough the aidstofithetdrill-head; aiapluralityao'f bits, each having a bifurcated tang adapted to be received in a slot and to be bent laterally thereby to lock the bit from longitudinal displacement;

a retainer having a plurality of openings for the passage therethrough of the tangs, the openings 5 being spaced to correspond to the slots so that the tangs will be positioned for entrance therein whereby all the tangs may be forced simultaneously into the slots; and means for centering the -retainer. relative .to the l drill-head.

.5. .Addrillehead provfde'd with a'central passage;

a plurality of wings projecting radially from the taxis of the drill-head, each wing having a substantially parallel sided slot extending across its -end and directed at an acute angle to a plane passingthrough the axis of the drill-head, the central passagebeing counterbored adjacent the slots; a aplunalityz'of :bitsxhaving tangs adapted to be receivedinthe slots and displaced laterally thereby tolock the bits from longitudinal displaceun-ent; 1a retaineriforlcarrying ;the. bits to zposittionttheir ,tangs .forisimultaneously entering the -'-slots the; retainenhaving .a central'opening *and imeansacarriedrby the; retainer for engaging the =.'counterbore: toa-alignthe :central openingwith the icentralma-ssage.

r6. -.A-.drill-head: havingrtwdsubstantially paralileltsided slots: iirits end iextending transversely. of the axistof thevdrilleheadwand .converging in the .directiona.of rthe :said axis towards .the said end; and aibit havingi'a bifurcated tang, the parts of which areradapted to bezreceivedain the slots and rbesspreadiapant thereby .tO-IOQkithG bitfrom longitudinal displacement.

-7. A drill+head having a ;,groove extending-.35 :across the .endi-thereof; 2aisubstantiallyparallel sided slotinithe bottom;of= the; groove directed at zaneacute-wang-le toaiplaneivpassing through the aaxis-zofa-the drill-head; iandra .bit .having a tang iadaptedito rbe areceived in the groove, the .free :40 rend-10f atheitangbeing adapted to ;be received in ithe :slot-sanddzo the displaced. laterally thereby to lock it ifromilongitudinal adisplacement.

:8.:For';use with ma Ldrillhead ;.formed with a :qaa'rallel s'sided sgroove :parallel =ito the axis 1 of the345 'bitaand'wzithsa substantiallwfiatzsidedislot :of. less swi-dthzthan'zthegroove extending from the bottom of the groove at one siderthereof transversely of "the dnilleheadzan'dxat. an -angleltothe axis of the drillehead; whitformedlwithaazparallel sided neck adapted to fit the groove andaitan'g to: fit the slot, 17116: said tanglbeing iof ductiileimaterial whereby though normally substantially straight it will be bent when forced iritotthe 'slot toslockthebit in place.

9. For use rwithra :drill-head .formed with a cparallelzsidedagroove parallel .to :the axis of the bit and with two substantially'ifiatisi'ded slots of Bless ivs'ridth thanrthergrocvecextending from the .bottom of theigmnvefand diverging in :the dime- 'Etion 1of '1 the saxis rof athe :drill-hea'd, 2a bit formed t with 'a Tparalilssided neck :adapted to .fit the groove and with tangs to fit the slots, the-said itarrgstbeingcof ductile material whereby though normally substantially straight they will; be: bentwvhienziorced into athe zsiots b130,.100k the bit in rpiaice. 

